Virus-free sweet potato seedlings are based on the characteristics of no virus or low virus concentration in the growing point of sweet potato stem tip. Using the method of combining biological technology and detoxification culture, the virus in sweet potato was effectively removed, and virus-free strains were obtained, and then a large number of virus-free sweet potato seedlings were cultured through asexual reproduction in a strict aseptic environment. The yield has been greatly increased, generally by more than 30%, and some varieties have even doubled. At the same time, the quality is also greatly improved, and the performance of the product is also greatly improved. The following describes the cultivation and daily management of sweet potato virus-free seedlings:

Cultivation and Transplanting of Virus-free Seedlings of 1. Sweet Potato

The virus-free seedlings of sweet potato obtained by rooting and strong seedling culture were moved to the seedling raising shed for about 5 days, and then the bottle cap of the culture bottle was opened for 2 days. In the evening or when the temperature is low, the medium attached to the roots should be rinsed clean, and the 1000-fold carbendazim solution should be soaked and disinfected for 20 minutes. After disinfection, put the virus-free seedlings on the bed frame to dry until the roots are slightly dry and white, and then set aside. The seedling substrate is generally stirred with 1000 times carbendazim solution three days in advance until the soil is wet but cannot squeeze out water, and then covered with plastic film for later use. In the process of cleaning and transplanting, try not to damage the root system. Plant spacing is controlled at about 10cm, and a single plant is directly planted in the shed to control aphids. After 60 days of transplanting, cuttings can be propagated once, and then every 2 weeks.

Daily Management of 2. Sweet Potato Virus-free Seedlings after Transplanting

1. Spray 1000 times carbendazim solution every week at the initial stage of transplanting virus-free sweet potato seedlings, and 800 times polymycetin solution every month in the middle and late stages.

2, when planting, should be fully watered, later every 2 to 3 days watering. The frequency of watering should be determined according to the weather conditions and should not be too wet to prevent root rot.

3. Fertilizer is applied once 15 days after planting, and then once every two weeks. Urea and compound fertilizer are used in turn at a concentration of 1000 times. A small amount of construction should be carried out frequently.

4. Take preventive measures against diseases and insect pests, and regularly check the insect-proof net to prevent the virus spread by insect, whitefly, etc. from infecting virus-free sweet potato seedlings again.

Field Planting and Management Technology of 3. Sweet Potato Virus-free Seedlings

1. Base fertilizer and top dressing

Generally, 2000-3000kg of organic fertilizer, 50kg of superphosphate and 20kg of potassium sulfate are applied per mu of land, and 10kg of urea is applied per mu of land in the early stage of growth.

(2) Transplantation

The ridge spacing is 75~100cm, and the ridge height is 30~40cm. Spray 1% urea solution in the whole nursery 3 days before cutting seedlings. After cutting seedlings, place them in a cool place. Do not pile them too high. Heat and rett. A better time for planting is after 15:00 p.m., it can be carried out all day on a cloudy day, and the dry soil should be watered with rooting water. 3000 to 500 plants should be planted per acre of land.

3. Site management

Sweet potato virus-free seedlings were planted for about 20 days. After the vines are dragged down, the sides of the ridge can be plowed and bleached for 1 day. The fertilizer is spread, returned, pressed and planted on the ridge, applying 15-20kg urea and 25-30kg potassium sulfate per 667 m2. In the intermediate stage, when the tubers grow up, fertilize twice with a solution of 0.7% potassium dihydrogen phosphate and 0.3% urea. Although sweet potatoes are drought-tolerant, they require a lot of water, and water management should focus on soil moisture.